Coated article with IR reflecting layer(s) and silicon zirconium oxynitride layer(s) and method of making same

ABSTRACT

A low-emissivity (low-E) coating includes first and second infrared (IR) reflecting layers of or including a material such as silver. The coating includes a bottom dielectric portion including a layer of or including silicon zirconium oxynitride, and a center dielectric portion including a layer of or including zinc stannate. The coating is configured to realize a combination of desirable visible transmission, consistent and low emissivity values, thermal stability upon optional heat treatment such as thermal tempering, desirable U-value, desirable LSG value, and desirable coloration and/or reflectivity values to be achieved. In certain example embodiments, an absorber layer sandwiched between a pair of dielectric layers may be provided in. Coated articles herein may be used in the context of insulating glass (IG) window units, or in other suitable applications such as monolithic window applications, laminated windows, and/or the like.

This invention relates to a coated article having a low-emissivity(low-E) coating including at least first and second infrared (IR)reflecting layers of or including a material such as silver or the like.The low-E coating is designed so that the coated article can realize oneor more of: desirable visible transmission, consistent and lowemissivity values, thermal stability upon optional heat treatment suchas thermal tempering, a low U-value, a desirable LSG value, anddesirable coloration and/or reflectivity values. In certain exampleembodiments, the coating includes a bottom dielectric portion includinga layer of or including silicon zirconium oxynitride, and a centerdielectric portion including a layer of or including zinc stannate. Ithas been found that the combination of at least the bottom dielectricportion including a layer of or including silicon zirconium oxynitride,and center dielectric portion including a layer of or including zincstannate, allows for a combination of desirable visible transmission,consistent and low emissivity values, thermal stability upon optionalheat treatment such as thermal tempering, desirable U-value, desirableLSG value, and desirable coloration and/or reflectivity values to beachieved. In certain example embodiments, an absorber layer sandwichedbetween a pair of dielectric layers may be provided in order to tailorvisible transmission such as when lower visible transmission coatingsare desired. Coated articles herein may be used in the context ofinsulating glass (IG) window units, or in other suitable applicationssuch as monolithic window applications, laminated windows, and/or thelike.

BACKGROUND AND SUMMARY OF EXAMPLE EMBODIMENTS OF THE INVENTION

Coated articles are known in the art for use in window applications suchas insulating glass (IG) window units, vehicle windows, monolithicwindows, and/or the like. In certain example instances, designers ofcoated articles often strive for a combination of desirable visibletransmission, desirable color, low emissivity (or emittance), low sheetresistance (R_(s)), desirable LSG values, and/or desirable U-values inthe context of IG window units. Desirable visible transmission anddesired coloration may permit coated articles to be used in applicationswhere these characteristics are desired such as in IG or vehicle windowapplications, whereas low emissivity and low sheet resistance permitsuch coated articles to block significant amounts of IR radiation so asto reduce for example undesirable heating of vehicle or buildinginteriors.

Low-E coatings are typically deposited on a glass substrate bysputtering. Emissivity and/or sheet resistance values of a coating orcoated article are driven in large part by the IR reflecting layer(s)which is/are typically made of silver or the like. However, it has beendifficult to achieve low tolerance variation with respect to emissivityvalues of such coatings. In other words, a problem in the art has beendifficulty in achieving a desired low emissivity value and/or sheetresistance value within a given small tolerance variation. The tolerancevariation has been larger than desired.

In view of the above, it will be appreciated that there exists a need inthe art for a coated article including a low-E coating that is designedso that a desired low emissivity value can be achieved within a givensmall tolerance range (e.g., a tolerance of plus/minus 1%). It wouldalso be desirable to provide such a coating that also achieves one ormore of: high visible transmission, low emissivity, thermal stabilityupon optional heat treatment such as thermal tempering, a low U-value,and desirable coloration and/or reflectivity values.

Conventionally, it has been difficult to achieve desirable LSG valuesand low ΔE* values (e.g., glass side reflective) in coatings having twosilver based IR reflecting layers. In example embodiments of thisinvention, it has surprisingly been found that desirable LSG values andlow ΔE* values (e.g., glass side reflective) in coatings having twosilver based IR reflecting layers are achievable, in combination withother desirable optical characteristics, when the following arecombined: (a) the second IR reflecting layer comprising silver isthicker than the first IR reflecting layer comprising silver, morepreferably when second IR reflecting layer is at least 10 angstroms (Å)thicker (more preferably at least 20 angstroms thicker, even morepreferably at least 30 angstroms thicker, and most preferably at least40 angstroms thicker) than the first IR reflecting layer comprisingsilver; (b) provision of the bottom dielectric portion including a layerof or including silicon zirconium oxynitride, (c) center dielectricportion including a layer(s) of or including zinc stannate; (d) azirconium silicon oxynitride based layer in the bottom dielectricportion of the layer stack is thicker (preferably at least 10 angstromsthicker, more preferably at least 20 angstroms thicker, and mostpreferably at least 30 angstroms thicker) than is a zinc stannate basedlayer in the bottom dielectric portion of the layer stack; (e) at leastone zinc stannate based layer in the center dielectric portion of thelayer stack is thicker (preferably at least 20 angstroms thicker, morepreferably at least 40 angstroms thicker, and most preferably at least60 angstroms thicker) than is a zirconium silicon oxynitride based layerin the bottom dielectric portion of the layer stack; and optionally (f)the absorber 14 in the center stack sandwiched between a pair of siliconnitride inclusive layers 13, 13′.

In certain example embodiments of this invention, it has been found thatthe combination of at least the bottom dielectric portion including alayer of or including silicon zirconium oxynitride, and centerdielectric portion (between IR reflecting layers) including a layer ofor including zinc stannate, allows for a combination of desirablevisible transmission, consistent and low emissivity values, thermalstability upon optional heat treatment such as thermal tempering,desirable U-value, desirable LSG value, and desirable coloration and/orreflectivity values to be achieved. In certain example embodiments, anabsorber layer sandwiched between a pair of dielectric layers may beprovided in order to tailor visible transmission such as when lowervisible transmission coatings are desired. A layer of or includingzirconium silicon oxynitride in the lower dielectric portion of thecoating, between the glass substrate and the lowermost IR reflectinglayer (e.g., of silver or the like) improves the quality of the IRreflecting layer thereby permitting the coated article to realized lowemissivity values with low tolerance variations. Providing zirconiumsilicon oxynitride under a layer of or including zinc stannate and undera layer of or including zinc oxide, in the lower dielectric portion ofthe coating, has surprisingly been found to improve the quality of thesilver and thus lower emissivity values and lower emissivity tolerancevalues in a desirable manner. Even though the zirconium siliconoxynitride is not directly contacting the IR reflecting layer, it stillimproves the quality of the overlying IR reflecting layer therebypermitting thermal properties of the coating to be improved andmanufactured in a more consistent manner. The IR reflecting layer hasbeen found to grow better and have a smoother base which can more easilybe repeated on a consistent basis. It has also been found that theprovision of a layer of or including titanium oxide (e.g., TiO₂) overthe zirconium silicon oxynitride results in an increase in visibletransmission of the coated article and improved optical properties ifdesired, as well as an increase in line speed.

In an example embodiment of this invention, there is provided a coatedarticle including a coating supported by a glass substrate, the coatingcomprising moving away from the glass substrate: a dielectric layercomprising zirconium silicon oxynitride; a first layer comprising zincstannate; a first layer comprising zinc oxide located over and directlycontacting the layer comprising zinc stannate; a first infrared (IR)reflecting layer comprising silver located on the substrate over anddirectly contacting the first layer comprising zinc oxide; and a contactlayer comprising metal oxide located over and directly contacting thefirst IR reflecting layer comprising silver; a second layer comprisingzinc stannate on the glass substrate over at least the first IRreflecting layer and the contact layer; a second layer comprising zincoxide located over at least the second layer comprising zinc stannate; asecond IR reflecting layer comprising silver located over at least thefirst IR reflecting layer, the first and second layers comprising zincstannate, and the first and second layers comprising zinc oxide; anotherdielectric layer over at least the second IR reflecting layer comprisingsilver; wherein the coating contains two silver based IR reflectinglayers; wherein the second IR reflecting layer comprising silver is atleast 10 angstroms (Å) thicker than the first IR reflecting layercomprising silver; wherein the dielectric layer comprising zirconiumsilicon oxynitride is at least 10 angstroms (Å) thicker than the firstlayer comprising zinc stannate; and wherein the second layer comprisingzinc stannate is at least 20 angstroms (Å) thicker than the dielectriclayer comprising zirconium silicon oxynitride.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a coated article according to anexample embodiment of this invention.

FIG. 2 is a cross sectional view of a coated article according toanother example embodiment of this invention.

FIG. 3 is a cross sectional view of a coated article according toanother example embodiment of this invention, including the stack forExamples 2, 4 and 6.

FIG. 4 is a cross sectional view of a coated article according toanother example embodiment of this invention, including the stack forExamples 1, 3 and 5.

FIG. 5 is a schematic diagram illustrating layers stacks according tovarious example embodiments of this invention, including layer stacksfor Examples 7-10.

FIG. 6 is a chart illustrating optical, thermal, and performance datafor Examples 1-6.

FIG. 7 is a chart illustrating optical, thermal, and performance datafor Examples 7-10.

FIG. 8 is a chart illustrating optical, thermal, and performance datafor Examples 11-14.

FIG. 9 is a cross sectional view of a coated article according toanother example embodiment of this invention, including the stack forExamples 11 and 13.

FIG. 10 is a cross sectional view of a coated article according toanother example embodiment of this invention, including the stack forExamples 12 and 14.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Referring now to the drawings in which like reference numerals indicatelike parts throughout the several views.

Coated articles herein may be used in applications such as monolithicwindows, IG window units that include a monolithic coated article,vehicle windows, and/or any other suitable application that includessingle or multiple substrates such as glass substrates.

Certain embodiments of this invention relate to a coated article havinga low-emissivity (low-E) coating supported by a glass substrate 1, thelow-E coating including at least first and second infrared (IR)reflecting layers of or including silver or the like. For example, seeIR reflecting layers 9 and 19 in FIG. 1. The low-E coating is designedso that the coated article can realize a combination of: desirablevisible transmission, consistent and low emissivity values, thermalstability upon optional heat treatment such as thermal tempering, a lowU-value, a desirable LSG value, and desirable coloration and/orreflectivity values. In certain example embodiments, the coatingincludes a bottom dielectric portion including a layer of or includingsilicon zirconium oxynitride 2, and a center dielectric portionincluding a layer of or including zinc stannate 12 and/or 15. It hasbeen found that the combination of at least the bottom dielectricportion including a layer of or including silicon zirconium oxynitride2, and center dielectric portion including a layer of or including zincstannate 12 and/or 15, allows for a combination of desirable visibletransmission, consistent and low emissivity values, thermal stabilityupon optional heat treatment such as thermal tempering, desirableU-value, desirable LSG value, and desirable coloration and/orreflectivity values to be achieved. In certain example embodiments, anabsorber layer 14 sandwiched between a pair of dielectric layers 13, 13′(e.g. of or including silicon nitride which may be doped with aluminumor the like) may be provided in order to tailor visible transmissionsuch as when lower visible transmission coatings are desired. Coatedarticles herein may be used in the context of insulating glass (IG)window units, or in other suitable applications such as monolithicwindow applications, laminated windows, and/or the like.

The provision of a layer of or including zirconium silicon oxynitride 2in the lower dielectric portion of the coating, between the glasssubstrate 1 and the IR reflecting layer (e.g., of silver or the like) 9improves the quality of the IR reflecting layer 9 thereby permitting thecoated article to realized low emissivity values with low tolerancevariations. And providing zirconium silicon oxynitride 2 under a layerof or including zinc stannate 5 and/or under a layer of or includingzinc oxide 7, in the lower dielectric portion of the coating, has beenfound to improve the quality of the silver and thus improve (lower)emissivity and lower emissivity tolerance values. Even though thezirconium silicon oxynitride 2 is not directly contacting the IRreflecting layer 9, it still surprisingly improves the quality of theoverlying IR reflecting layers thereby permitting thermal properties ofthe coating to be improved and manufactured in a more consistent manner.The IR reflecting layers 9 and 19 have been found to grow better andhave a smoother base which can more easily be repeated on a consistentbasis. It has also been surprisingly found that the provision of a layerof or including titanium oxide (e.g., TiO₂) 3 over the zirconium siliconoxynitride 2 results in an increase in visible transmission of thecoated article and improved optical properties, as well as an increasein line speed.

The terms “heat treatment” and “heat treating” as used herein meanheating the article to a temperature sufficient to achieve thermaltempering, heat bending, and/or heat strengthening of the glassinclusive article. This definition includes, for example, heating acoated article in an oven or furnace at a temperature of least about 580degrees C., more preferably at least about 600 degrees C., for asufficient period to allow tempering, bending, and/or heatstrengthening. In certain instances, the HT may be for at least about 4or 5 minutes. The coated article may or may not be heat treated indifferent embodiments of this invention.

FIG. 1 is a cross sectional view of a coated article according to anexample embodiment of this invention. The coated article includes glasssubstrate 1 (e.g., clear, green, bronze, or blue-green glass substratefrom about 1.0 to 10.0 mm thick, more preferably from about 1.0 mm to6.0 mm thick, with an example glass substrate being a clear glasssubstrate about 3.8 to 4.0 mm thick), and a multi-layer low-E coating(or layer system) provided on the substrate 1 either directly orindirectly. As shown in FIG. 1, the low-E coating includes: dielectriclayer of or including zirconium silicon oxynitride 2, dielectric layerof or including titanium oxide (e.g., TiO₂) 3, dielectric layers 5, 12,15 of or including zinc stannate, dielectric layers 7 and 17 of orincluding zinc oxide which may optionally be doped with a metal such asSn or Al, IR reflecting layers 9 and 19 of or including silver, gold, orthe like, upper contact layers 11 and 21 of or including Ni, Cr, NiCr,NiCrMo, or any oxide thereof such as an oxide of NiCr or an oxide ofNiCrMo, dielectric layer 22 of or including a metal oxide such as tinoxide (e.g., SnO₂), zinc stannate, or the like, and dielectric layer 23of or including a material such as silicon nitride (e.g., Si₃N₄) and/orsilicon oxynitride, and an optional dielectric overcoat layer (notshown) of a material such as zirconium oxide (e.g., ZrO₂). In order totailor the visible transmission of the coating to a desired value thecoating may also include an absorber layer 14 provided between a pair ofdielectric layers 13, 13′ of or including silicon nitride or the like.The absorber layer 14 is preferably metallic or substantially metallic(contains from 0-10% oxygen, more preferably from 0-5% oxygen, atomic%), and may be of or include NiCr, NiCrMo, NbZr, or the like. It isnoted that “C22” is a NiCrMo based material, which may be used for theabsorber layer 14 in certain example embodiments. Other layers and/ormaterials may additionally be provided in certain example embodiments ofthis invention, and it is also possible that certain layers may beremoved or split in certain example instances. For example, optionally alayer of or including silicon nitride and/or silicon oxynitride (notshown) may be provided between the glass substrate 1 and the zirconiumsilicon oxynitride 2. Moreover, other materials may be used forparticular layers instead of the materials mentioned above in certainexample embodiments of this invention.

FIG. 2 is a cross sectional view of a coated article according toanother example embodiment of this invention. FIG. 2 illustrates thatlayers 13, 13′ and 14 from the FIG. 1 embodiment may be omitted, incertain example embodiments of this invention.

FIGS. 3-5 are cross sectional views of coated articles includingcoatings according to example embodiments of this invention, withexample thicknesses (d) of layers in units of nm being listed forpurposes of example.

In monolithic instances, the coated article includes only one substratesuch as glass substrate 1. However, monolithic coated articles hereinmay be used in devices such as IG window units for example. Typically,an IG window unit may include two spaced apart glass substrates, with agap defined therebetween. Example IG window units are illustrated anddescribed, for example, in U.S. Pat. Nos. 5,770,321, 5,800,933,6,524,714, 6,541,084 and US 2003/0150711, the disclosures of which areall hereby incorporated herein by reference. An example IG window unitmay include, for example, the coated glass substrate of any of FIGS. 1-5coupled to another glass substrate via spacer(s), sealant(s) or the likewith a gap being defined therebetween. This gap between the substratesin IG unit embodiments may in certain instances be filled with a gassuch as argon (Ar), or a mixture of air and argon gas. An example IGunit may comprise a pair of spaced apart substantially clear glasssubstrates each about 4 mm (e.g., 3.8 mm) thick one of which is coatedwith a coating herein in certain example instances, where the gapbetween the substrates may be from about 5 to 30 mm, more preferablyfrom about 10 to 20 mm, and most preferably about 16 mm. In certainexample instances, the coating may be provided on the side of theouter/exterior glass substrate 1 facing the gap (although the coatingmay be on the other substrate in certain alternative embodiments), whichis often referred to as surface two of the IG window unit.

In certain example IG unit embodiments of this invention, the coating isdesigned such that the resulting IG unit (e.g., with, for referencepurposes, a pair of 3.8 mm clear glass substrates spaced apart by 16 mmwith a mixture of air and Ar gas in the gap) has a U-value of no greaterthan 1.4 W/(m²K), more preferably no greater than 1.3 W/(m²K), sometimesno greater than 1.1 W/(m²K), and sometimes no greater than 1.0 W/(m²K).U-value herein is measured and referred to in accordance with EN410-673_2011—Winter, the disclosure of which is hereby incorporatedherein by reference. Indeed, it is preferred that the optical andthermal features discussed herein are achieved when the coating containstwo silver-based IR reflecting layers (e.g., as shown in FIGS. 1-5), asopposed to a single or triple-silver layer stack.

The nitrogen/oxygen ratio in the zirconium silicon oxynitride layer 2has been found to be significant in certain example embodiments. Toomuch oxygen in zirconium silicon oxynitride layer 2 may result in areduced sputter rate and does not seem to help reduce absorption orincrease transmission. Too much oxygen in this layer 2 may result inundesirable haze. Accordingly, in certain example embodiments of thisinvention, the layer 2 of or including zirconium silicon oxynitride hasa nitrogen to oxygen ratio (nitrogen/oxygen ratio) of at least 1 morepreferably of at least 3, more preferably at least 4, and even morepreferably at least 5 (using atomic %). Thus, for example, layer 2 maycontain at least three times more N than 0, more preferably at leastfour times as much N than O, and most preferably at least five times asmuch N than O. For example in certain example embodiments of thisinvention, layer 2 is sputter-deposited using a ZrSi target, using fromabout 0.4 to 2.0, more preferably from about 0.5 to 1.5, and mostpreferably about 0.8 to 1.0 ml/kW O₂ gas, and from about 4.0 to 10.0,more preferably from about 5.0 to 8.0, and most preferably from about6.0 to 7.0 ml/kW N₂ gas. Argon (Ar) gas may also be used in thesputtering process.

Moreover, it has also been found that, in zirconium silicon oxynitridelayer 2, too much Zr may result in an undesirably brittle material andtoo little Zr may cause the silver layer 9 to be not as smooth anddegrades coating qualities. It has been found that better results inthese respects are achieved when the layer 2 contains more Si than Zr(atomic %). For example, the Zr/Si (atomic) ratio in layer 2 (and in thesputtering target for depositing layer 2) is preferably from 0.20 to0.60, more preferably from 0.30 to 0.47, and most preferably from 0.35to 0.44. For example, a sputtering target(s) containing about 40% Zr andabout 60% Si may be used to sputter-deposit layer 2.

Dielectric layer 3 may be of or include titanium oxide in certainexample embodiments of this invention. The titanium oxide of layer 3 mayin certain example instances be represented by TiO_(x), where x is from1.5 to 2.5, most preferably about 2.0. The titanium oxide may bedeposited via sputtering or the like in different embodiments. Incertain example instances, dielectric layer 3 may have an index ofrefraction (n), at 550 nm, of at least 2.0, more preferably of at least2.1, and possibly from about 2.3 to 2.6 when the layer is of or includestitanium oxide. In certain embodiments of this invention, the thicknessof titanium oxide inclusive layer 3 is controlled so as to allow a*and/or b* color values (e.g., transmissive, film side reflective, and/orglass side reflective) to be fairly neutral (i.e., close to zero) and/ordesirable. Other materials may be used in addition to or instead oftitanium oxide in certain example instances. In certain alternativeembodiments, the Ti in oxide layer 3 may be replaced with another metal.

In example embodiments, the dielectric zinc stannate (e.g., ZnSnO,Zn₂SnO₄, or the like) based layers 5, 12 and/or 15 may optionallyinclude more Zn than Sn by weight. For example, the metal content of oneor more of these zinc stannate based layers may include from about51-90% Zn and from about 10-49% Sn, more preferably from about 51-70% Znand from about 30-49% Sn, with an example being about 52% Zn and about48% Sn (weight %, in addition to the oxygen in the layer) in certainexample embodiments of this invention. Thus, for example, the zincstannate based layers may be sputter-deposited using a metal targetcomprising about 52% Zn and about 48% Sn in certain example embodimentsof this invention. Optionally, the zinc stannate based layers may bedoped with other metals such as Al or the like. In certain optionalembodiments, it is possible to dope the zinc stannate (e.g., ZnSnO) withother materials such as Al, Zn, N, or the like. The zinc stannate basedlayers are substantially or substantially fully oxided in preferredembodiments of this invention.

Layers 7 and 17 in certain embodiments of this invention are of orinclude zinc oxide (e.g., ZnO). The zinc oxide of these layers maycontain other materials as well such as Al (e.g., to form ZnAlO_(x)) orSn. For example, in certain example embodiments of this invention, oneor more of zinc oxide layers 7, 17 may be doped with from about 1 to 10%Al, more preferably from about 1 to 5% Al, and most preferably about 1to 4% Al. The zinc oxide layer(s) 7 and/or 17, in combination with thezinc stannate and zirconium silicon oxynitride 2, helps improve silverquality and emissivity characteristics of the coating.

Dielectric layers 13, 13′, 23 may be of or include silicon nitride incertain embodiments of this invention. Silicon nitride may, among otherthings, improve heat-treatability of the coated articles, e.g., such asthermal tempering or the like, and may or may not include some oxygen.The silicon nitride of these layers may be of the stoichiometric type(i.e., Si₃N₄), or alternatively of the Si-rich type in differentembodiments of this invention.

Infrared (IR) reflecting layers 9, 19 are preferably substantially orentirely metallic and/or conductive, and may comprise or consistessentially of silver (Ag), gold, or any other suitable IR reflectingmaterial. IR reflecting layers help allow the coating to have low-Eand/or good solar control characteristics. The IR reflecting layers may,however, be slightly oxidized in certain embodiments of this inventionand may optionally be doped with other material such as Pd or the like.The coating preferably contains two IR reflecting layers 9, 19 inpreferred embodiments of this invention.

Conventionally, it has been difficult to achieve desirable LSG valuesand low ΔE* values (e.g., glass side reflective) in coatings having twosilver based IR reflecting layers. In example embodiments of thisinvention, it has surprisingly been found that desirable LSG values andlow ΔE* values (e.g., glass side reflective) in coatings having twosilver based IR reflecting layers are achievable, in combination withother desirable optical characteristics, when the following arecombined: (a) the second IR reflecting layer comprising silver 19 isthicker than the first IR reflecting layer comprising silver 9, morepreferably when second IR reflecting layer 19 is at least 10 angstroms(Å) thicker (more preferably at least 20 angstroms thicker, even morepreferably at least 30 angstroms thicker, and most preferably at least40 angstroms thicker) than the first IR reflecting layer comprisingsilver 9; (b) provision of the bottom dielectric portion including alayer of or including silicon zirconium oxynitride 2, (c) centerdielectric portion including a layer(s) of or including zinc stannate 12and/or 15; (d) zirconium silicon oxynitride based layer 2 in the bottomdielectric portion of the layer stack is thicker (preferably at least 10angstroms thicker, more preferably at least 20 angstroms thicker, andmost preferably at least 30 angstroms thicker) than is the zinc stannatebased layer 5 in the bottom dielectric portion of the layer stack; (e)at least one zinc stannate based layer (e.g., 12) in the centerdielectric portion of the layer stack is thicker (preferably at least 20angstroms thicker, more preferably at least 40 angstroms thicker, andmost preferably at least 60 angstroms thicker) than is the zirconiumsilicon oxynitride based layer 2 in the bottom dielectric portion of thelayer stack; and optionally (f) the absorber 14 in the center stacksandwiched between a pair of silicon nitride inclusive layers 13, 13′.

The upper contact layers 11, 21 may be of or include nickel (Ni) oxide,chromium/chrome (Cr) oxide, or a nickel alloy oxide such as nickelchrome oxide (NiCrO_(x)), NiCrMoO_(x), or other suitable material(s)such as Ni, Ti or an oxide of Ti, or NiTiO_(x), in certain exampleembodiments of this invention. The use of, for example, NiCrO_(x) inthese layers allows durability to be improved. These layers may be fullyoxidized in certain embodiments of this invention (i.e., fullystoichiometric), or alternatively may only be partially oxidized (i.e.,sub-oxide). In certain instances, the NiCrO_(x) layer 11 may be at leastabout 50% oxidized. Descriptions of various types of oxidation gradedcontact layers that may optionally be used are set forth in U.S. Pat.No. 6,576,349, the disclosure of which is hereby incorporated herein byreference. Contact layer 11 may or may not be continuous in differentembodiments of this invention across the entire underlying IR reflectinglayer 9.

Transparent dielectric layer 22 may be of or include tin oxide incertain example embodiments of this invention. However, it may be dopedwith certain other materials in other example embodiments, such as withAl or Zn in certain example alternative embodiments.

Other layer(s) below or above the illustrated coating may also beprovided. Thus, while the layer system or coating is “on” or “supportedby” substrate 1 (directly or indirectly), other layer(s) may be providedtherebetween. Thus, for example, the coating of FIG. 1 or FIG. 2 may beconsidered “on” and “supported by” the substrate 1 even if otherlayer(s) are provided between layer 2 and substrate 1. Moreover, certainlayers of the illustrated coating may be removed in certain embodiments,while others may be added between the various layers or the variouslayer(s) may be split with other layer(s) added between the splitsections in other embodiments of this invention without departing fromthe overall spirit of certain embodiments of this invention.

While various thicknesses may be used in different embodiments of thisinvention, example thicknesses and materials for the respective layerson the glass substrate 1 in the FIG. 1 embodiment are as follows, fromthe glass substrate 1 outwardly (e.g., the Al content in the zinc oxidelayers may be from about 1-10%, more preferably from about 1-3% incertain example instances):

TABLE 1 (Example Materials/Thicknesses; FIG. 1 Embodiment) PreferredMore Example Layer Range ({acute over (Å)}) Preferred ({acute over (Å)})(Å) ZrSiO_(x)N_(y) (layer 2)  20-300 Å  50-200 Å  90-160 Å TiO_(x)(layer 3)  15-150 {acute over (Å)}  20-60 Å  30 Å ZnSnO (layer 5) 20-150 Å  30-80 Å  45-65 Å ZnAlO_(x) (layer 7)  40-170 Å  50-100 Å 65-90 Å Ag (layer 9)  50-130 Å  80-120 Å  90-110 Å NiCrO_(x) (layer 11) 10-70 Å  15-35 Å  20-30 Å ZnSnO (layer 12) 170-500 Å 210-400 Å 230-270Å Si₃N₄ (layer 13)  50-350 Å 100-200 Å 120-160 Å absorber (layer 14) 40-210 Å  60-150 Å  80-140 Å Si₃N₄ (layer 13')  50-350 Å 100-200 Å120-160 Å ZnSnO (layer 15)  20-300 Å 100-200 Å 130-170 Å ZnAlO_(x)(layer 17)  40-500 Å  50-400 Å  65-200 Å Ag (layer 19)  90-200 Å 130-180Å 130-150 Å NiCrO_(x) (layer 21)  10-70 Å  15-35 Å  20-30 Å SnO₂ (layer22)  50-400 Å 100-300 Å 130-180 Å Si₃N₄ (layer 23)  50-400 Å 150-280 Å190-240 Å

In certain example embodiments of this invention, coated articlesaccording to the FIG. 1 and/or FIG. 2 embodiments herein may have thefollowing characteristics set forth in Table 2 when measuredmonolithically or in an IG window unit, and these values refer to bothheat treated and non-heat treated embodiments. Note that E_(n) is normalemissivity/emittance.

TABLE 2 Low-E/Solar Characteristics (HT or non-HT) CharacteristicGeneral More Preferred Most Preferred R_(s) (ohms/sq.): <= 8.0 <= 7.0 <=5.0  E_(n): <= 4% <= 3% <= 2.5%

Moreover, coated articles including coatings according to the FIG. 1 andFIG. 2 embodiments of this invention may have the followingoptical/color/thermal stability characteristics (e.g., when thecoating(s) is provided on a clear soda lime silica glass substrate 1from 1 to 10 mm thick, preferably about 4 mm thick such as 3.8 mmthick), as shown in Table 3 below. In Table 4, all parameters aremeasured monolithically. Note that “f” stands for film side, and “g”stands for glass side. Thus, R_(f)Y is film side reflectance, which isvisible reflectance measured form the film side of the coated substrate.And R_(g)Y is glass side reflectance, which is visible reflectancemeasured form the glass side of the coated substrate. Glass sidereflectance, and glass side reflective color values a*_(g) and b*_(g)are typically deemed to be the most important when the coating isprovided on surface two of an IG window unit because this indicates howthe outside of the building will appear. Note that ΔE* is a valueindicative of thermal stability, and in particular how much the opticalcharacteristics changes upon heat treatment (HT) such as thermaltempering. The lower a ΔE* value, the less the applicable a*, b* and L*values change upon HT (e.g., thermal tempering). The low ΔE* values ofthe coatings discussed herein demonstrate that HT and non-HT versions ofeach coating substantially matching with respect to coloration. Notethat the equation for determining ΔE* is known in the art and isdescribed for example in U.S. Pat. No. 8,263,227, the disclosure ofwhich is hereby incorporated herein by reference.

TABLE 3 Example Optical Characteristics (Monolithic, HT or non-HT)Characteristic General More Preferred T_(vis) (or TY)(Ill. C, 2 deg.):40-80% 45-78% a*_(t) (Ill. C, 2°): −7.0 to −2.0 −6.0 to −3.0 b*_(t)(Ill. C, 2°): −2.0 to +8.0 0.0 to +5.0 R_(f)Y (Ill. C, 2 deg.): <= 13%<= 11% or <= 10% a*_(f) (Ill. C, 2°): −11.0 to +8.0 −8.0 to +3.0 b*_(f)(Ill. C, 2°): −14.0 to +10.0 −11.0 to +1.0 ΔE*_(f): <= −4.0 or <= 2.0 <=1.5 R_(g)Y (Ill. C, 2 deg.): <= 13% <= 11% a*_(g) (Ill. C, 2°): −5.0 to+4.0 −3.0 to +1.0 b*_(g) (Ill. C, 2°): −20.0 to +10.0 −18.0 to −5.0ΔE*_(g): <= 2.5 or <= 2.0 <= 1.5

Examples 1-14

Examples 1-14 are provided for purposes of example only, and are notintended to be limiting. FIG. 3 shows the layer stacks for Examples 2, 4and 6, and FIG. 4 shows the layer stacks for Examples 1, 3 and 5. Thesecond layer stack in FIG. 5 is the layer stack for Examples 7 and 9,and the third layer stack in FIG. 5 is the layer stack for Examples 8and 10. FIG. 9 shows the layer stack for Examples 11 and 13, and FIG. 10shows the layer stack for Examples 12 and 14.

Data from Examples 1-14 is shown in FIGS. 6-8. In FIGS. 6-8, monolithicdata (AC or as coated) is shown, as is heat treated (HT) data such asfor thermal tempering. The data in the upper third of FIGS. 6-8 ismonolithic measured data, whereas the data in the center sections ofFIGS. 6-8 is IG data where the coating is provided on surface two of anIG window unit with 3.8-4.0 mm thick glass substrates. The siliconnitride layers were deposited by sputtering a silicon target (doped withabout 8% Al) in an atmosphere including argon and nitrogen gas. FIGS.6-8 demonstrate that the Examples were able to achieve, in the contextof a double silver coating, a combination of: desirable visibletransmission, consistent and low emissivity values, thermal stabilityupon optional heat treatment such as thermal tempering, a low U-value, adesirable LSG value, and desirable coloration and/or reflectivityvalues.

In an example embodiment of this invention, there is provided a coatedarticle including a coating supported by a glass substrate, the coatingcomprising moving away from the glass substrate: a dielectric layercomprising zirconium silicon oxynitride; a first layer comprising zincstannate; a first layer comprising zinc oxide located over and directlycontacting the layer comprising zinc stannate; a first infrared (IR)reflecting layer comprising silver located on the substrate over anddirectly contacting the first layer comprising zinc oxide; and a contactlayer comprising metal oxide located over and directly contacting thefirst IR reflecting layer comprising silver; a second layer comprisingzinc stannate on the glass substrate over at least the first IRreflecting layer and the contact layer; a second layer comprising zincoxide located over at least the second layer comprising zinc stannate; asecond IR reflecting layer comprising silver located over at least thefirst IR reflecting layer, the first and second layers comprising zincstannate, and the first and second layers comprising zinc oxide; anotherdielectric layer over at least the second IR reflecting layer comprisingsilver; wherein the coating contains two silver based IR reflectinglayers; wherein the second IR reflecting layer comprising silver is atleast 10 angstroms (Å) thicker than the first IR reflecting layercomprising silver; wherein the dielectric layer comprising zirconiumsilicon oxynitride is at least 10 angstroms (Å) thicker than the firstlayer comprising zinc stannate; and wherein the second layer comprisingzinc stannate is at least 20 angstroms (Å) thicker than the dielectriclayer comprising zirconium silicon oxynitride.

The coated article of the immediately preceding paragraph may furthercomprise an absorber layer sandwiched between and contacting first andsecond dielectric layers comprising silicon nitride, between the firstand second IR reflecting layers. The absorber layer may be of or includeNi and Cr, and/or Ni, Cr and Mo. The absorber layer may be metallic orsubstantially metallic.

In the coated article of any of the preceding two paragraphs, the secondIR reflecting layer comprising silver may be at least 20 angstroms (Å)thicker than the first IR reflecting layer comprising silver, morepreferably at least 40 angstroms (Å) thicker than the first IRreflecting layer comprising silver.

In the coated article of any of the preceding three paragraphs, thedielectric layer comprising zirconium silicon oxynitride may be at least20 angstroms (Å) thicker than the first layer comprising zinc stannate.

In the coated article of any of the preceding four paragraphs, thesecond layer comprising zinc stannate may be at least 40 angstroms (Å)thicker than the dielectric layer comprising zirconium siliconoxynitride, more preferably at least 60 angstroms (Å) thicker than thedielectric layer comprising zirconium silicon oxynitride.

In the coated article of any of the preceding five paragraphs, the layercomprising zirconium silicon oxynitride may contain at least three timesas much nitrogen as oxygen.

In the coated article of any of the preceding six paragraphs, a ratio ofZr/Si (atomic) may be from 0.30 to 0.47 in the layer comprisingzirconium silicon oxynitride, more preferably from 0.35 to 0.44.

In the coated article of any of the preceding seven paragraphs, theremay be a layer comprising titanium oxide over and directly contactingthe layer comprising zirconium silicon oxynitride.

In the coated article of any of the preceding eight paragraphs, thelayer comprising zirconium silicon oxynitride may directly contact theglass substrate.

In the coated article of any of the preceding nine paragraphs, the layercomprising zirconium silicon oxynitride may be from about 50-200 Åthick.

In the coated article of any of the preceding ten paragraphs, measuredmonolithically the coated article may have a visible transmission of atleast 40%.

In the coated article of any of the preceding eleven paragraphs, thecontact layer may comprise Ni and/or Cr.

In the coated article of any of the preceding twelve paragraphs, thecoated article may be configured to have a glass side reflective ΔE*value of no greater than 2.5 due to heat treatment sufficient forthermal tempering, more preferably no greater than 1.5 due to heattreatment sufficient for thermal tempering.

The coated article of any of the preceding thirteen paragraphs mayfurther comprise: an absorber layer sandwiched between and contactingfirst and second dielectric layers comprising silicon nitride, betweenthe first and second IR reflecting layers; a third layer comprising zincstannate located over the absorber layer and over the first and seconddielectric layers comprising silicon nitride; wherein the third layercomprising zinc stannate is located under and directly contacting thesecond layer comprising zinc oxide.

The coated article of any of the preceding fourteen paragraphs may beprovided in an IG window unit, wherein the IG window unit has a U-valueof no greater than 1.1, the IG window unit further comprising anotherglass substrate, and wherein the coating may be on surface two of the IGwindow unit.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

The invention claimed is:
 1. A coated article including a coatingsupported by a glass substrate, the coating comprising moving away fromthe glass substrate: a dielectric layer comprising zirconium siliconoxynitride; a first layer comprising zinc stannate; a first layercomprising zinc oxide located over and directly contacting the layercomprising zinc stannate; a first infrared (IR) reflecting layercomprising silver located on the substrate over and directly contactingthe first layer comprising zinc oxide; and a contact layer comprisingmetal oxide located over and directly contacting the first IR reflectinglayer comprising silver; a second layer comprising zinc stannate on theglass substrate over at least the first IR reflecting layer and thecontact layer; a second layer comprising zinc oxide located over atleast the second layer comprising zinc stannate; a second IR reflectinglayer comprising silver located over at least the first IR reflectinglayer, the first and second layers comprising zinc stannate, and thefirst and second layers comprising zinc oxide; another dielectric layerover at least the second IR reflecting layer comprising silver; whereinthe coating contains two silver based IR reflecting layers; wherein thesecond IR reflecting layer comprising silver is at least 10 angstroms(Å) thicker than the first IR reflecting layer comprising silver;wherein the dielectric layer comprising zirconium silicon oxynitride isat least 10 angstroms (Å) thicker than the first layer comprising zincstannate; and wherein the second layer comprising zinc stannate is atleast 20 angstroms (Å) thicker than the dielectric layer comprisingzirconium silicon oxynitride.
 2. The coated article of claim 1, whereinthe coating further comprises an absorber layer sandwiched between andcontacting first and second dielectric layers comprising siliconnitride, between the first and second IR reflecting layers.
 3. Thecoated article of claim 2, wherein the absorber layer comprises Ni andCr.
 4. The coated article of claim 2, wherein the absorber layercomprises Ni, Cr and Mo.
 5. The coated article of claim 2, wherein theabsorber layer is metallic or substantially metallic.
 6. The coatedarticle of claim 1, wherein the second IR reflecting layer comprisingsilver is at least 20 angstroms (Å) thicker than the first IR reflectinglayer comprising silver.
 7. The coated article of claim 1, wherein thesecond IR reflecting layer comprising silver is at least 40 angstroms(Å) thicker than the first IR reflecting layer comprising silver.
 8. Thecoated article of claim 1, wherein the dielectric layer comprisingzirconium silicon oxynitride is at least 20 angstroms (Å) thicker thanthe first layer comprising zinc stannate.
 9. The coated article of claim1, wherein the second layer comprising zinc stannate is at least 40angstroms (Å) thicker than the dielectric layer comprising zirconiumsilicon oxynitride.
 10. The coated article of claim 1, wherein thesecond layer comprising zinc stannate is at least 60 angstroms (Å)thicker than the dielectric layer comprising zirconium siliconoxynitride.
 11. The coated article of claim 1, wherein the layercomprising zirconium silicon oxynitride contains at least three times asmuch nitrogen as oxygen.
 12. The coated article of claim 1, wherein aratio of Zr/Si (atomic) is from 0.30 to 0.47 in the layer comprisingzirconium silicon oxynitride.
 13. The coated article of claim 1, whereina ratio of Zr/Si (atomic) is from 0.35 to 0.44 in the layer comprisingzirconium silicon oxynitride.
 14. The coated article of claim 1, whereina layer comprising titanium oxide is located over and directlycontacting the layer comprising zirconium silicon oxynitride.
 15. Thecoated article of claim 1, wherein the layer comprising zirconiumsilicon oxynitride directly contacts the glass substrate.
 16. The coatedarticle of claim 1, wherein the layer comprising zirconium siliconoxynitride is from about 50-200 Å thick.
 17. The coated article of claim1, wherein measured monolithically the coated article has a visibletransmission of at least 40%.
 18. The coated article of claim 1, whereinthe contact layer comprises Ni and/or Cr.
 19. The coated article ofclaim 1, wherein the coated article is configured to have a glass sidereflective ΔE* value of no greater than 2.5 due to heat treatmentsufficient for thermal tempering.
 20. The coated article of claim 1,wherein the coated article is configured to have a glass side reflectiveΔE* value of no greater than 1.5 due to heat treatment sufficient forthermal tempering.
 21. The coated article of claim 1, wherein thecoating further comprises: an absorber layer sandwiched between andcontacting first and second dielectric layers comprising siliconnitride, between the first and second IR reflecting layers; a thirdlayer comprising zinc stannate located over the absorber layer and overthe first and second dielectric layers comprising silicon nitride;wherein the third layer comprising zinc stannate is located under anddirectly contacting the second layer comprising zinc oxide.
 22. An IGwindow unit comprising the coated article of claim 1, wherein the IGwindow unit has a U-value of no greater than 1.1, the IG window unitfurther comprising another glass substrate, and wherein the coating ison surface two of the IG window unit.
 23. A coated article including acoating supported by a glass substrate, the coating comprising movingaway from the glass substrate: a dielectric layer comprising zirconiumsilicon oxynitride; a first layer comprising zinc stannate; a firstlayer comprising zinc oxide located over and directly contacting thelayer comprising zinc stannate; a first infrared (IR) reflecting layercomprising silver located on the substrate over and directly contactingthe first layer comprising zinc oxide; and a contact layer comprisingmetal oxide located over and directly contacting the first IR reflectinglayer comprising silver; a second layer comprising zinc stannate on theglass substrate over at least the first IR reflecting layer and thecontact layer; a second layer comprising zinc oxide located over atleast the second layer comprising zinc stannate; a second IR reflectinglayer comprising silver located over at least the first IR reflectinglayer, the first and second layers comprising zinc stannate, and thefirst and second layers comprising zinc oxide; another dielectric layerover at least the second IR reflecting layer comprising silver; whereinthe coating contains two silver based IR reflecting layers; and whereinthe coating is characterized by at least one of: (a) the second IRreflecting layer comprising silver is at least 10 angstroms (Å) thickerthan the first IR reflecting layer comprising silver; (b) the dielectriclayer comprising zirconium silicon oxynitride is at least 10 angstroms(Å) thicker than the first layer comprising zinc stannate; and (c) thesecond layer comprising zinc stannate is at least 20 angstroms (Å)thicker than the dielectric layer comprising zirconium siliconoxynitride.
 24. The coated article of claim 23, wherein the coating ischaracterized by at least two of (a), (b) and (c).